1. Field of the Invention
The present invention relates to a pair of shutter glasses for viewing stereo images, and more particularly, to a pair of shutter glasses capable of viewing a plurality of types of monitors whose image light outputs have different polarization directions.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating a construction of conventional three-dimensional (3D) glasses 100 and related optical principals thereof. As shown in FIG. 1, the 3D glasses 100 are utilized by a user for viewing a monitor 110 which generates an image light output with a polarization direction at 135 degrees. Each lens of the 3D glasses 100 comprises a front polarized lens 102, a liquid crystal (LC) layer 104 and a back polarized lens 106. In accordance with the operation of the 3D glasses 100, the voltage VLC on the LC layer 104 determines whether light is allowed to transmit through the lens. For example, when the voltage VLC on the LC layer 104 is 0V, light transmitted through the LC layer 104 has its polarization direction changed to 45 degrees, and then transmits through the back polarized lens 106 successfully; on the contrary, when the voltage VLC on the LC layer 104 is 12V, light transmitted through the LC layer 104 has its polarization direction still maintained at 135 degrees, and fails to transmit through the back polarized lens 106. Therefore, by providing control voltages to LC layers corresponding to the left-eye lens and the right-eye lens alternately, 3D glasses 100 may let the user's left eye and right eye respectively receive suitable images, leading superimposed images regarded as stereo images in the user's brain.
However, the 3D glasses 100 shown in FIG. 1 are only suitable for monitors whose image light outputs have polarization directions at 135 degrees, rather than monitors whose image light outputs have other polarization directions, such as TN (Twisted Nematic) liquid crystal display (LCD) apparatus whose polarization direction is 45 degrees, IPS (In-plane Switching) LCD apparatus whose polarization direction is 0 degree, VA (Vertical Alignment) LCD apparatus whose polarization direction is 90 degrees, etc. So, since 3D glasses 100 may not be suitable for all types of monitors, manufacturers have to redesign 3D glasses according to each monitor type, and the production cost is increased inevitably. Besides, one user has to buy a plurality of 3D glasses suitable for a plurality of types of monitors, resulting in unnecessary waste.